JP2000065060A - Initial adjusting method of magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically adjust a drift and gain of a sensor by automatically initially adjusting a magnetic bearing device by vibrating the magnetic bearing device so as to bring it into contact with a rotary body protecting bearing by reducing gain of a control means. SOLUTION: A reference signal and a feedback signal from a control object 24 are imparted to an adder 21 so that these are subtracted. Position detecting sensor output is used as the feedback signal from the control object 24. Output of the adder 21 is imparted to a proportional circuit 22, a proportional constant K is multiplied, and a main control circuit 23 is a driving circuit for driving respective magnetic bearings. The control object 24 is driven by the main control circuit 23. When the proportional constant K of the proportional circuit 22 is reduced, gain of a control system reduces, and control becomes unstable, so that a rotary shaft contacts with the bearings. The vibrational center is determined from a maximum value and a minimum value of the sensor output, and a difference from a present offset quantity is added or subtracted. Gain and an offset quantity are repeatedly adjusted to obtain stable rotation of the rotary shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an initial adjustment method for a magnetic bearing device, for example, a magnetic bearing used for a vacuum pump for obtaining a high vacuum and for magnetically rotating a rotating shaft of a turbo molecular pump spindle. In the device,
The present invention relates to an initial adjustment method for initially adjusting offset amounts and gains of a plurality of position sensors.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration of a conventional magnetic bearing spindle. In FIG. 3, a magnetic bearing spindle 1 for a turbo molecular pump has a rotating shaft 3 provided in a case 2, and a thrust magnetic bearing 4 provided substantially at the center of the rotating shaft 3 and a thrust magnetic bearing 4. The radial magnetic bearings 5 and 6 provided above and below support the rotating shaft 3 in the thrust and radial directions in a non-contact manner, and are rotationally driven by a driving motor 7. The radial position of the rotating shaft 3 is determined by the radial position sensors 8 and 9.
And the thrust position is detected by the thrust position sensor 10. Further, a protective ball bearing 1 for bearing the rotating shaft 3 when the radial magnetic bearings 5 and 6 are abnormal.
Reference numerals 1 and 12 are arranged above and below the rotating shaft 3.

The detection output of each of the sensors 8, 9, 10 is given to a controller 20 provided externally, and the controller 20 controls each of the magnetic bearings 4, 5, and 6 according to a command from an external system controller 30, and By driving the rotating shaft 7, the rotating shaft 3 of the magnetic bearing spindle 1 rotates.

[0004]

In the magnetic bearing spindle 1 shown in FIG. 3, each of the sensors 8, 9, 10 has a rotary shaft when the offset amount and the sensor gain appearing in the respective outputs are different from the design values. 3 may vibrate and come into contact with the protective ball bearings 11 and 12, so that stable rotation may not be obtained. For this purpose, it is necessary to accurately measure and adjust the offset amount and the gain of each of the sensors 8, 9, and 10.

[0005] Therefore, a main object of the present invention is to provide an initial adjustment method for a magnetic bearing device that can automatically adjust the drift and gain of each sensor.

[0006]

The invention according to claim 1 is
A plurality of position sensors for detecting the position of the rotating body, a magnetic bearing that magnetically supports the rotating body in a non-contact manner, a magnetic bearing body having a protective bearing for protecting the rotating body, and a plurality of position sensors. In a magnetic bearing device provided with control means for controlling the magnetic bearing based on the detection signal, the gain of the control means is reduced to vibrate the rotating body so as to come into contact with the protective bearing, and based on the outputs of the plurality of position sensors. To automatically make initial adjustments.

In the invention according to claim 2, the offset amount and the gain of the plurality of position detection sensors are adjusted for the plurality of position sensor outputs of claim 1.

In the invention according to claim 3, the adjusting operation of claim 1 or 2 is repeated several times.

[0009]

FIG. 1 is a block diagram of one embodiment of the present invention. Although only one control loop is shown in FIG. 1, this control loop is provided for each control axis. The adder 21 is provided with the reference signal and the feedback signal from the control target 24, and these are subtracted. As the feedback signal from the control target 24, the outputs of the position detection sensors 8, 9, and 10 shown in FIG. 3 are used. The output of the adder 21 is applied to a proportional circuit 22 and multiplied by a proportional constant K, and applied to a main control circuit 23. Here, the main control circuit 23 controls each magnetic bearing 4,
This is a drive circuit for driving 5,6. Then, the control target 24 is driven by the main control circuit 23.

FIG. 2 is a timing chart for explaining the operation of one embodiment of the present invention. When the proportional constant K of the proportional circuit 22 shown in FIG. 1 is reduced, the gain of the control system to be adjusted decreases, the control becomes unstable, and the rotating shaft 3
Contacts the protective ball bearings 11 and 12. That is, the gain is gradually lowered from the stable state, and when a sensor output as shown in FIG. 2 is obtained at several Hz, the rotating shaft 3 comes into contact with the protective ball bearings 11 and 12. Then, the center of the vibration is obtained from the maximum value and the minimum value, and the difference between the current offset amount and 0 V is added to or subtracted from the sensor output.

Further, if the sensor gain is adjusted to a specified amplitude and the sensor characteristic is non-linear, the offset amount changes when the gain is adjusted, but the above adjustment is repeated until the gain and the offset amount converge. in this way,
By repeatedly adjusting the gain and offset,
The rotating shaft 3 can be stably rotated.

[0012]

As described above, according to the present invention, the rotating body is brought into contact with the protective bearing by lowering the gain of the control system corresponding to each control shaft, and the initial adjustment is performed based on the position sensor output at that time. By doing so, stable rotation can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the embodiment of the present invention;

FIG. 3 is a diagram showing a configuration of a conventional magnetic bearing spindle.

[Explanation of symbols]

 Reference Signs List 21 adder 22 proportional circuit 23 main control circuit 24 controlled object 1 magnetic bearing spindle 3 rotating shaft 4 thrust magnetic bearing 5,6 radial magnetic bearing 8,9 radial position sensor 10 thrust position sensor

Continuation of the front page F term (reference) 3J102 AA01 BA03 BA19 CA14 CA20 DA02 DA03 DA09 DB05 DB10 DB11 DB37 GA06 5H607 AA12 AA14 BB01 BB14 CC01 CC03 CC07 DD03 FF06 GG21 HH01

Claims (3)

[Claims] 1. A magnetic bearing body comprising: a plurality of position sensors for detecting a position of a rotating body; a magnetic bearing for supporting the rotating body in a non-contact manner; and a protection bearing for protecting the rotating body. And a control device for controlling the magnetic bearing based on detection signals from the plurality of position sensors, wherein the rotating body is protected by reducing a gain of a control system of the control device. A method for initial adjustment of a magnetic bearing device, comprising: vibrating so as to contact a bearing; and automatically performing initial adjustment based on the outputs of the plurality of position sensors. 2. The method for initial adjustment of a magnetic bearing device according to claim 1, wherein an offset amount and a gain of the plurality of position detection sensors are adjusted for the plurality of position sensor outputs. 3. The initial adjustment method for a magnetic bearing device according to claim 1, wherein the adjustment operation is repeated several times.